About the 10 reps for three times remark. Is that wrong? No mate it's not, that's fine as long as your muscles are being worked just before failure. You can go heavier and aim for 6 or 8 reps or go lighter and aim for 12 or even sometimes on occasion more. Up the sets too, 4 is the norm but it's not uncommon to do 3 - 6, mix this around for different exercises.
I tend to aim low for the heavier compound lifts, so with bench press I tend to do 6 - 8 reps I might sometimes do 10 on weight I normally do 8 reps for if I want to really push myself to failure. The same goes for Squats and Deadlifts. I rarely do 12 reps for these three exercises but this is only my own personal preference, I enjoy lifting really heavy on these. The same for Military press actually, it's not classified as one of the three major lifts but I treat it as one because it helps you lift heavy for such lifts like Olympic, Clean and Jerk or Max Axle.
On the smaller lifts I will do 12 often, so for example cable, machine or dumbbell flies. Tricep pull downs, skull crushers, hammer curls, bent over rows... the list goes on. But I do still tend to aim for 10, 8 or 6. It really depends, as Arnold used to say you need to shock the muscles, do things it's not used to, trick your body into growth because your body gets used to routine.
Some really good advise for you would be to develop a mind-muscle connection, when you're doing reps think about what muscle you're meant to be engaging and make them do most of the work. Think of your arms like levers (but obviously still use them) during chest and back exercises to get the full potential out of your workout, this will help target the muscle better and exhaust it quicker. Ensure you're also using full range of motion, no half repetitions.
